Do the majority of fish lack scales on their heads?

Question

Based on pictures, it seems to me that a vast majority of fish species that have scales do NOT have scales on their heads. **Is that fact true?** To make this properly answerable: - lets' define a "majority" as >70% of fish species. But frankly, I'm more interested in actual numerical answer than whether it passes some arbitrary threshold or not. - The universe which I'm interested in measuring the percentage are fish species that have "normal" (Cycloid and ctenoid is the technical term, I believe?) scales on their bodies. If that's not specific enough, you can restrict the universe to species in Actinopterygii (ray-finned) that have scales.

Answer 1

You are at least partially right from your observations. For example, within the family Tripterygiidae, most species lack scales on their head, or have highly modified types of scales. A comparative study of 48 species showed that only 2 have "normal" scales of their head. Many fish may have large head plate like scales or have scales that are few and far between. Heck there are even some toadfish for example that lack scales all together. But I would at say that in certain families of fish this is a true statement based on your observations.

Great Question!